Jinxiu Wang ^a, Zhen Liu ^a, Wen Jin ^a, Yongxiao Tuo ^b*, Yan Zhou ^c, Shanshan Zhou ^a, Tingting Gong ^a, Jiamei Li ^a, Yuting Ni ^a, Min Wang ^a*, Luhua Jiang ^a*

^a College of Materials Science & Engineering, Qingdao University of Science & Technology, Qingdao, 266042, P.R. China.

^b State Key Laboratory of Heavy Oil Processing, College of New Energy, China University of Petroleum (East China) Qingdao, Shandong 266580, P. R. China.

^c Phonon Engineering Research Center of Jiangsu Province, Center for Quantum Transport and Thermal Energy Science, Institute of Physics Frontiers and Interdisciplinary Sciences, School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China.

*Corresponding authors: E-mail: yxtuo@upc.edu.cn; wmin@qust.edu.cn;luhuajiang@qust.edu.cn

Keywords: CO₂ electrochemical reduction, In-situ characterization,Cu₂OSO₄@CuO catalyst,In-situ Evolution,DFT calculations

Abstract

Real-time tracking the dynamic structure reconstruction of Cu-based catalysts during CO₂ reduction reaction (CO₂RR) and identifying the active sites of catalysts are essential for fundamental understanding on electrocatalysis and thereby rational design of catalysts. However, the exact relationship between structure reconstruction and CO₂RR performance remains poorly understood, thus bringing great challenges to rationally designing catalysts and understanding the reaction mechanism. Herein, by virtue of comprehensive in-situ and ex-situ studies, the dynamic structure reconstruction of Cu₂OSO₄@CuO is elucidated, and it is demonstrated that Cu₂OSO₄@CuO evolves to S-incorporated Cu₂O@Cu (S-Cu₂O@Cu). In-situ surface-enhanced infrared absorption spectroscopy (SEIRAS) and density functional theory (DFT) calculations reveal that Cu₂O is conducive to the generation of *CO, while the incorporation of S downshifts the d-band center of Cu in Cu₂O, facilitating desorption and sequent migration of *CO and *COH to undergo C-C coupling. Consequently, a maximal FE(C₂₊) of as high as 88% with a partial current density of –609 mA cm^–2 is achieved for the reconstructed Cu₂OSO₄@CuO, which outperforms the state-of-the-art Cu-based catalyst. This work not only highlights the significant role of the incorporation of sulfur in enhancing the CO₂RR activity over Cu₂O, but also provides a feasible strategy to obtain stabilized Cu₂O electrocatalyst for CO₂RR.